The role of solid-phase basicity on heat evolution during hardening of cements

Usherov-Marshak, A. V.; Schroeyers, Wouter; Pershina, L. A.

doi:10.1016/s0008-8846(98)00113-6

Cited by 5 publications

(5 citation statements)

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“…The mechanism of hydration of so-called low basic cements (the cements with the lower basicity of a solid phase compared to that of traditional cements; an example is the alkali-activated cement) [ 16 ]. Its hydration is completely different and is caused not by the protonization of ionic bonds, but by the break of covalent Si-O-Si and Al-O-Al bonds, followed by the synthesis of low hydration phases from the destruction products resulting in activation of the hydration process when the temperature rises from 20 to 40 °C.…”

Section: Resultsmentioning

confidence: 99%

“…Calorimetry of OPC cement is quite well studied [ 9 , 10 , 11 , 12 ]. However, as shown by calorimetric studies of alkali-activated cements, its interpretation cannot be automatically applied to these cements due to hydration processes.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to OPC-based cements, alkali-activated cements have an inverse relationship between strength and heat release [ 15 , 16 ]. The hydration of alkali-activated cements is accompanied by low heat of hydration, but at an early age their strength is quite high [ 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

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Calorimetric Studies of Alkali-Activated Blast-Furnace Slag Cements at Early Hydration Processes in the Temperature Range of 20–80 °C

et al. 2021

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In the hydration process of inorganic cements, the analysis of calorimetric measurements is one of the possible ways to better understand hydration processes and to keep these processes under control. This study contains data from the study of thermokinetic processes in alkali-activated blast-furnace slag cements compared to ordinary Portland cement (OPC). The obtained results show that, in contrast to ОРС, the heat release values cannot be considered as a characteristic of the activity of alkali-activated blast-furnace slag cements. In addition, it is concluded that in the case of OPC cements, cumulative heat release is a criterion for the selection of effective curing parameters, while in the case of alkali-activated blast-furnace slag cements, a higher heat rate (which increases sharply with increasing temperature from 20 to 40 °С) is a criterion. From the point of views of thermokinetics, the rate of heat release at temperatures up to 40 °С can be a qualitative criterion that allows to choose the parameters of heat curing of alkali-activated cement concretes. By introducing a crystallo-chemical hardening accelerator, such as Portland cement clinker, into the composition of alkali-activated blast-furnace slag cements, it is possible to accelerate the processes not only in the condensation-crystallization structure formation stage, but also in the dispersion-coagulation structure formation stage. Portland cement clinker increased the efficiency of thermal curing at relatively non-high temperatures.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Calorimetric Studies of Alkali-Activated Blast-Furnace Slag Cements at Early Hydration Processes in the Temperature Range of 20–80 °C

et al. 2021

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“…The main physicomechanical parameters of raw and synthesized materials were determined with the help of a complex of modern physical and chemical methods of analysis, the method of laser granulometry, X-ray phase analysis, optical and raster electron microscopy calorimetric analysis [12][13][14], etc.…”

Section: Methodsmentioning

confidence: 99%

Properties of Composite Gypsum Binders Depending on Multicomponent Mineral Additives

Lesovik

Чернышева

Drebezgova

2019

MSF

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This article considers the possibility of increasing the effectiveness of composite gypsum binders (CGB) by controlling the processes of structure formation as a result of using new types of multicomponent mineral additives that are significantly different from the traditionally used quartz raw materials:- waste of wet magnetic separation of ferrous quartzites (WMS waste,) of polymineral composition with quartzy of varying degrees of crystallinity, nanodispersed silica and chalk powder. We have studied the cause-effect relationship between the change in the ratio of binding and mineral additives of various compositions, which determines the conditions for the formation of technological and strength characteristics of the projected composite materials with specified performance properties. We have established the presence of regularities in the changes in the properties of CGB, the composition of the hardening products and the microstructure depending on the type and content of gypsum binders of β-and α-modifications, portland cement, multicomponent finely-dispersed mineral additives, the regularity consists in the binding of portlandite, which is released upon portland cement hydration, by the amorphous phase of earth siliconas a part ofnanodispersed powder and chalcedony variety of quartz waste of wet magnetic separation of ferruginous quartzites. This provides a reduction in the basicity of the solidifying system, the intensification of crystal formation, and the formation of newgrowths with a high content of tobormorite-low-basic calcium hydrosilicates that compact the microstructure of the hardening matrix and, as a result, increase the water resistance and stability. It is noted that this mechanism of hydration of CGB minimizes inner stresses and volume deformations, therefore the number of microcracks decreases, which leads to an increase in its efficiency in comparison with the traditionally used gypsum binder and that differs from the traditional portland cement by a fast strength generation.

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“…Frost on the study of concrete slag containing cement determined by the ice formation during freezing-thawing method of determining which set out in detail in [6][7][8][9]. According to [10], the connection between the brand of frost resistance and the amount of ice formed in the concrete during freezing, is shown in Table . 1.…”

Section: Raw Materials and Methods Of Testsmentioning

confidence: 99%

Ice Formation as an Indicator of Frost-Resistance on the Concrete Containing Slag Cement in Conditions of Freezing and Thawing

Moskalenkо

Runova

2016

MSF

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The connection with the icing on the frost resistance of concrete containing slag cement and chemical additives «MC Bauchemie» under freezing and thawing.It is shown that freeze concrete samples at (-) 10°C increase in the amount of slag from 30 to 70 wt.% Of binder in the composition leads to an increase in the index of ice formation in the concrete of 1.7 ... 1.9 times compared with the concrete obtained at a slag containing slag cement with a content of 10 wt.%. Frost resistance of concrete is reduce from F450 to F400.When freezing of concrete samples at (-) 20°C increase in the amount of slag from 30 to 50 wt. % Binder in the composition leads to an increase in the index of ice formation in the concrete of 1.7 times compared with the concrete obtained on slag cement containing slag with a content of 10 wt.%. Frost resistance of concrete is reduce from F400 to F350.The concrete on the slag containing cement with slag 70 wt. % is observed a slight decrease in ice formation. However, its value is 1.4 times higher than ice formation in concretes containing slag in an amount of 10 wt. %. Mark on frost resistance remains at F350.The smallest ice formation, regardless of the content of the slag into the slag containing cement, concrete characterized in that use complex organo-mineral supplement SX (5%) + SP (0.6%) in the amount of 5.6%. According to the degree of influence of additives used to reduce ice formation in the slag in concretes, containing cements can be ranker number: SX (5%) + SP (0.6%) > NC (5%) + SP (0.6%) > SP (0.6%).

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The role of solid-phase basicity on heat evolution during hardening of cements

Cited by 5 publications

References 1 publication

Calorimetric Studies of Alkali-Activated Blast-Furnace Slag Cements at Early Hydration Processes in the Temperature Range of 20–80 °C

Calorimetric Studies of Alkali-Activated Blast-Furnace Slag Cements at Early Hydration Processes in the Temperature Range of 20–80 °C

Properties of Composite Gypsum Binders Depending on Multicomponent Mineral Additives

Ice Formation as an Indicator of Frost-Resistance on the Concrete Containing Slag Cement in Conditions of Freezing and Thawing

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